Shaving gels, on the other hand, are formulated in such a way that the preparation also containing an aerosol can be removed from the container in non-foamed form, whereby it later foams on the skin or in the hand through vaporization of the propellant contained in the preparation in response to body heat.
In both cases, the skill of the formulation consists of attaining a good compromise in respect to foam texture, gel consistency, stability and visual appearance through a suitable choice of thickening agents and foam stabilizers.
A frequent ingredient of such preparations is cocamide DEA. This compound belongs to the group of fatty acid diethanolamides. It is a reaction product from diethanolamine (DEA), from the family of alkanolamines and free fatty acids, obtained from coconut oil. Free DEA, which only occurs in significant amounts in poor qualities, is able to form nitrosamines in combination with N-nitrosating substances, such as nitrites. As these nitrosamines exhibit a carcinogenic potential, it is therefore advisable to avoid their formation. This can easily be achieved through correct use of the raw material. Unfortunately, chemical correlations are often depicted inaccurately or even incorrectly in publications, e.g. in consumer magazines. As a result, although fatty acid diethanolamides can indeed be used in brand products, the desire to avoid their use has meanwhile become prevalent.
In surfactant preparations, fatty acid diethanolamides exhibit the additional benefit of acting as a so-called “foam booster”: at the same time, the stability, formation and structure of the foam is significantly improved, in other words several requirements are fulfilled by an ingredient at the same time. Consequently, there is no alternative to cocamide DEA in shaving preparations, as the unique combination of all properties is not attained.
It would be desirable to find an ingredient with similar effects, which does not manifest the problem described above. As this problem has been known for quite some time, many substitutes for fatty acid diethanolamides have already been revealed. Despite the wide range offered, no suitable substitute could so far be found, which can advantageously be used in shaving preparations and which fulfills all the above requirements at the same time in a comparable quality.
International patent application WO 96/09032 discloses soap-free shaving preparations based on sarcosinates with a pH value in the region pH 5-7. In contrast to this, preparations corresponding to the invention contain soap and exhibit a pH value >7.
Patent specification U.S. Pat. No. 3,923,970 discloses shaving preparations which, amongst other ingredients, contain polyoxyethylene oleyl ethers with an HLB in the range 1-9 or lauramide DEA. In contrast to this, preparations corresponding to the invention are free of these.
Patent specification EP 503004 discloses shaving preparations which, amongst other ingredients, contain polysiloxane/polyether copolymers. In contrast to this, preparations corresponding to the invention are free of these.
The international patent application WO 98/33473 discloses shaving preparations which, amongst other ingredients, contain polyethoxylated polyvinylpyrrolidones. In contrast to this, preparations corresponding to the invention are free of these.
European patent application 576615 discloses self-foaming O/W shaving creams containing water, soap components, surfactant, propellant, emollients and foam stabilizers from the group of fatty alkanolamides, e.g. lauramide DEA. Nevertheless, no information is disclosed concerning preparations with an additional content of cellulose derivatives while free of fatty acid alkanolamides at the same time.